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Y.S. Huh,
Y. Choi, K.J. Hong,
J.H. Jung,
W. Hu,
J.H. Kang,
B.J. Min,
S.H. Shin,
H.K. Lim,
M.S. Song,
H.W. Park
[show abstract]
[hide abstract]
ABSTRACT: A Geiger-mode avalanche photodiode (GAPD) array-based MRI compatible PET is being developed in our laboratory. The purpose of this study is to develop filtering methods for PET event signals contaminated by RF pulses for simultaneous PET-MR imaging. The detector for the MRI compatible PET was composed of LYSO scintillators coupled with GAPD arrays. PET signal acquisition was implemented by a FPGA-based data acquisition (DAQ) system. The noise caused by RF field of MRI has large effect on PET signal acquisition when PET detectors are placed inside MRI. In this study, software, hardware and hybrid filtering methods were evaluated. The software method utilizes a maximum rise window and an integration (energy) window for real time RF noise rejection. The hardware method uses differential to single ended circuit including low-pass filter. The hybrid method combines software and hardware method. Our preliminary results demonstrate that the RF pulse effect on PET DAQ could be reduced by the software or hardware method developed in this study and hybrid method is the best to minimize the interference of RF pulses.
Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE; 12/2009
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K.J. Hong,
Y. Choi,
J.H. Kang,
W. Hu,
J.H. Jung,
B.J. Min,
H.K. Lim,
S.H. Shin,
Y.S. Huh,
Y.H. Chung,
P. Hughes,
C. Jackson
[show abstract]
[hide abstract]
ABSTRACT: Geiger-mode avalanche photodiode (GAPD) has been demonstrated to be a high performance PET sensor because of high gain, fast response, low excess noise, low bias voltage operation and magnetic field insensitivity. The purpose of this study is to develop a PET for human brain imaging using 4 ? 4 array of large size GAPD. PET detector modules were designed and built to develop a prototype PET. The PET consisted of 72 detector modules arranged in a ring with an inner diameter of 330 mm. The LYSO arrays consisted of 4 ? 4 array of 3 ? 3 ? 20 mm<sup>3</sup> pixels, which were 1-to-1 coupled to 4 ? 4 arrays of 9 mm<sup>2</sup> GAPD pixels (SensL, Ireland). The GAPDs were tiled together using flip chip technology on glass and operated at a bias voltage of 32 V for a gain of 3.5 ? 10<sup>6</sup>. The signals of the each module were amplified by a 16 channel preamplifier circuit with differential outputs and then sent to a position decoder circuit (PDC), which readout digital address and analog pulse of the one interacted channel from 64 signals of 4 preamplifier boards. The PDC output signals were fed into FPGA-embedded DAQ boards. The analog signal was sampled with 100 MHz, and arrival time and energy of the digitized signal were calculated and stored. The coincidence data were sorted and reconstructed by standard filtered back projection. The energy and time resolution of LYSO-GAPD block detector for 511-keV was 20.4% and 2.4 ns, respectively. The developed PDC could accurately provide the interacted PET signal and reduce the number of the readout channels of PET detector modules based on array type GAPD. The rods down to a diameter of 3.5 mm were resolved in hot-rod phantom image acquired with the brain PET which is similar to the image obtained by Monte Carlo simulation. Activity distribution pattern between white and gray matter in Hoffman brain phantom was well imaged. These results demonstrate that high performance PET could be developed using the GAPD-based PET dete-
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ctors, analog and digital signal processing methods designed in this work. The prototype brain PET will be tested in a clinical 3T MRI to construct a combined PET-MRI.
Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE; 12/2009
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[show abstract]
[hide abstract]
ABSTRACT: A dual-modality compact SPECT/CT system for small animal imaging was developed. The SPECT system consisted of a pinhole collimator and continuous NaI(Tl) scintillation crystal coupled to a PSPMT. The CT system consisted of a microfocus X-ray tube and a CMOS flat-panel detector. The SPECT system was mounted perpendicular to the X-ray system. Individual projections of the SPECT and the CT were acquired by rotating the animal on a vertical axis in front of the detectors. The SPECT and CT images were reconstructed using OSEM and Feldkamp's cone-beam algorithms, respectively. Mouse and rat SPECT images demonstrated detailed activity distribution at the expected structures. A CT image obtained with 40 kVp and 0.5 mA presented high-resolution anatomic details. Fused SPECT/CT images demonstrated good agreement between the CT images and the corresponding uptake of the radiotracer. The SPECT/CT system developed in this study provides high-quality dual-modality images and could be useful to obtain functional images with high resolution morphology information
IEEE Transactions on Nuclear Science 11/2006; · 1.45 Impact Factor
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Y S Huh,
Y Choi, K J Hong,
J H Jung,
W Hu,
J H Kang,
B J Min,
S H Shin,
H K Lim,
M S Song,
H W Park
[show abstract]
[hide abstract]
ABSTRACT: A Geiger-mode avalanche photodiode (GAPD) array-based MRI compatible PET is being developed in our laboratory. The purpose of this study is to develop filtering methods for PET event signals contaminated by RF pulses for simultaneous PET-MR imaging. The detector for the MRI compatible PET was composed of LYSO scintillators coupled with GAPD arrays. PET signal acquisition was implemented by a FPGA-based data acquisition (DAQ) system. The noise caused by RF field of MRI has large effect on PET signal acquisition when PET detectors are placed inside MRI. In this study, software, hardware and hybrid filtering methods were evaluated. The software method utilizes a maximum rise window and an integration (energy) window for real time RF noise rejection. The hardware method uses differential to single ended circuit including low-pass filter. The hybrid method combines software and hardware method. Our preliminary results demonstrate that the RF pulse effect on PET DAQ could be reduced by the software or hardware method developed in this study and hybrid method is the best to minimize the interference of RF pulses.
